Neutral Overvoltage - GE Multilin 350 Series Instruction Manual

S3 PROTECTION

Neutral overvoltage

NOTE:
NOTE
6–96
Courtesy of NationalSwitchgear.com
The relay has one Neutral Overvoltage element per protection group. This element requires
the three phase Bus VTs to be Wye connected. When setting the pickup for this element, it
is important to consider the error in the VT ratio, as well as the normal voltage unbalance
on the system.
This element should be used with caution. It would normally be applied to give line to
ground fault coverage on high impedance grounded or ungrounded systems, which are
isolated. This constraint stems from the fact that a measurement of 3V0 cannot
discriminate between a faulted circuit and an adjacent healthy circuit. Use of a time
delayed back-up or an alarm mode allow other protections an opportunity to isolate the
faulted element first.
The following path is available using the keypad. For instructions on how to use the
keypad, please refer to Chapter 3 - Working with the Keypad.
PATH:
SETPOINTS > S3 PROTECTION > SETPOINT GROUP 1(2) > NEUTRAL OV
NEUTRAL OV FUNCTION
Range: Disabled, Alarm, Latched Alarm,Trip
Default: Disabled
The selection of the Latched Alarm, Alarm, or Trip setting enables the Neutral OV
function. The output relay #1 "Trip" will operate if the function is selected as a Trip and
the neutral voltage is above the NTRL OV PKP setting for a time greater than the selected
NTRL OV DELAY time. The "ALARM" LED will not turn on if the neutral OV function is set to
Trip. The "ALARM" LED will flash upon an OV operating condition, with the neutral OV
function selected as Alarm, and will self-reset, when this operating condition clears. If
Latched Alarm is selected as a neutral OV function, the "ALARM" LED will flash during the
OV condition, and will stay "ON" after the condition clears, until the reset command is
initiated. The output relay #1 "Trip" will not operate if the Latched Alarm or Alarm setting
is selected. Any or all of the output relays 3 to 6 can be selected to operate when the
neutral OV function is selected as Latched Alarm, Alarm, or Trip.
NEUTRAL OV PKP
Range: 0.00 to 1.25 x VT in steps of 0.01
Default: 0.30 x VT
This setting defines the neutral OV pickup level.
NEUTRAL OV DELAY
Range: 0.1 to 600.0 sec in steps of 0.1 sec
Default: 2.0 s
This setting specifies the time delay before OV operation.
OUTPUT RELAY 3 to 6
Range: Do not operate, Operate
Default: Do not operate
Any or all of the output relays 3 to 6 can be selected to operate upon a Neutral OV
condition. The selection of relay outputs operation is available no matter whether
Latched Alarm, Alarm, or Trip function is selected.
BLOCK 1/2/3
Range: Off, Contact Input 1 to 10[8], Virtual Input 1 to 32, Remote Input 1 to 32, Logic
Element 1 to 16
Default: Off
Three blocking inputs are provided in the Neutral OV menu. One blocking input "high" is
enough to block the function. The available selections for each block include Contact
input, Virtual Input, Remote Input, or Logic Element.
350 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 6: SETPOINTS